Transformation mechanism of muddy carbonate rock by the coupling of bioturbation and diagenesis: A case study of the Cretaceous of the Mesopotamia Basin in the Middle East

YE Yu,LI Fengfeng,SONG Xinmin,GUO Rui

Fig. 4. Photos and schematic diagram of cast thin sections of Khasib Formation at 2665.40 m in Well A-12-8 in A Oilfield, the Middle East. (a) Panoramic scanning of a cast thin section which is dyed in red (left part) and undyed in white (right part); (b) Schematic difference of burrows and matrix; (c) Undyed, single polarized light. The field of vision is matrix that is muddy bioclastic and psammitic limestone, and the bioclasts are mainly benthic foraminifera. (d) Undyed, single polarized light. Within the field of vision, the matrix and burrows account for half respectively. The boundary between them is obvious, and the rock structure is significantly different. The burrows are of particle support structure, and the matrix shows mud pellet structure. (e) Dyed, single polarized light. The field of vision is burrows filled by bioclastic and psammitic limestone, presenting a grain supported structure, with well-developed intergranular pores.